Question

Suppose 8 people want to communicate with each other using public key encryption. The communication between any pair of them is visible to all of them but no other person other than the pair should be able to decode their communication. How many public and private keys are required for this group?

Answer 1

Answer:

The answer is "64"

Explanation:

There has been 1 Private Key 1 Public Key for every person. The private key is used for other app messages. All else uses the Public Key to encrypt messages with that user. Those keys are numerically related. Even if you have 5 users, you will be given 5 Personal keys and 5 Public keys.

• All user will have a duplicate of other public keys, which indicates (n*n-1) copies of n public keys on different systems to make sure shared contact between all users, plus n private keys.

• The unique key count is 2n, with n^2 distributed private and public keys on different systems.
• 8 people,  where 8 is a number, that is equal to n so, $n^2 = 8^2 =8 \times 8 = 64$